The invention relates to a time adjusting mechanism in an electronic wristwatch of the type having a setting shaft which is moved into and from operative connection with a correction wheel.
An adjusting mechanism of this type is known from DE-AS No. 29 47 400. It is characterized by a relatively simple configuration, because the drive of the time indicator hands is effected through a quartz-stabilized, electronically actuated stepping motor. That is, the setting shaft does not have to be structured and arranged to wind a force accumulator (i.e., a clockwork spring).
Such a known time adjusting mechanism possesses considerable advantages with respect to the simple layout and functionally safe actuation of a manual calender setting (which in the present adjusting mechanism for a wristwatch without a calendar display is not required). However, it also has the disadvantage that accessibility of the setting shaft to the hands mechanism for the manual setting of the hands is cumbersome in view of the structural parts required and the space needed within the mechanism for their operation. A particular disadvantage involves the need for a considerable open area for accommodating the correction wheel when the latter is displaced between its inoperative and adjusting positions in response to axial sliding of the setting stem or shaft. The provision of such space is contrary to the desire for a flat wristwatch configuration.
Concerning the requirements of a flat configuration and small dimensions of wristwatches, no significant improvement is obtained by using, in place of the correction wheel height control, a set wheel arranged coaxially in the area of the tip of the setting shaft and equipped with crown gearing. For the operationally effective functioning of such a gearing (the teeth of which are bent transversely with respect to the wheel), a large wheel diameter extending in height (i.e, parallel to the hands axis) is required. Also, such wheel must be placed in an area close to the center of the works, contrary to the goal of placing gears as close to the shaft as possible in order to reduce the structural height. Furthermore, a lateral (i.e., directed radially with respect to the axis of hands rotation) spring pressure would be necessary for maintaining the correction position, which is not comparible with the mode of operation of the commonly used automatic assembly installations for wristwatch mechanisms; such installations are, rather, based for operational reasons on an installation sequence in the direction of the axis of the mechanism.
Finally, it is possible, in particular in order to obtain a flat configuration wherein an actuation in the upward direction is fundamentally detrimental, to convert the axial displacement of the setting shaft into a correction position by way of a setting lever gear located under the setting shaft into a meshing displacement of the correction wheel parallel to the plane of the gears of the mechanism. This translation movement requires, however, long lever arms and, again, springs acting transversely to the works axis, together with a large number of cooperating individual parts; the components and their installation would require approximately one-fourth of the entire available surface, i.e., a quadrant adjacent to the setting shaft. This would require an expansion in either the height or surface area of the watch to house further operating parts, such as the electronic circuit, the surface area of the mechanism must be enlarged. To this is added the higher cost of the production, storage, installation and possibly the replacement during repairs of the numerous individual parts.
In view of these conditions, it is an object of the present invention to provide a time adjusting mechanism with a setting shaft of the above-described generic type, characterized by (i) a high operating safety, (ii) a minimal structural height of the works, and (iii) reduced manufacturing and installation efforts.